Conventional industrial processes to decaffeinate liquids such as, for example, coffee include: 1) solvent decaffeination, where a solvent such as ethyl acetate is used to extract caffeine from pre-wetted starting material such as, for example, green coffee beans; 2) super-critical carbon dioxide, which uses an inert gas (carbon dioxide) to act as a solvent and remove caffeine from starting material such as, for example, green coffee beans; and 3) water decaffeination, which uses an aqueous extract (e.g., aqueous coffee extract containing equilibrium quantities of the non-caffeine soluble solids but no caffeine) to extract essentially only caffeine from a starting material such as, for example, green coffee beans.
The use of clays, zeolites, activated carbon, or ion-exchange resins as decaffeination aids or processes has been reported in the literature, although these materials are not in wide-scale industrial use. Generally speaking, such materials are used to decaffeinate only caffeine-containing liquids. The removed caffeine cannot be easily recovered once it has adsorbed/absorbed onto clays, zeolites, activated carbon, or ion-exchange resins. In contrast, most conventional industrial decaffeination processes decaffeinate solid starting materials such as, for example, coffee beans. Such conventional industrial processes are generally designed to recover the caffeine which is sold as a chemical once removed from the coffee, tea, cola or other source.
In some decaffeination processes, bentonite clay is mixed with a liquid such as, for example, brewed coffee for about 45 minutes. The bentonite clay is removed by either settling/decanting, filtering, or centrifuging the slurry. Although a large proportion of the caffeine may be removed using this technique, separation of the bentonite clay from the liquid poses problems. A consumer would not wish to wait 45 minutes before having decaffeinated beverages (e.g., decaffeinated coffee), and would not have available centrifugation or the high-pressure filtration required to remove the bentonite.
Accordingly, there is a need for a practical device which uses an adsorbent to remove caffeine from liquids. For example, there is a need for a filter that incorporates clays or zeolites to adsorb caffeine from liquids in order to produce a practical consumer product. A need exists for a filter containing an adsorbent such as, for example, bentonite clays and/or zeolites which could be used in a similar manner as a conventional coffee filter (either basket- or cone-type) to decaffeinate up to an entire pot of coffee or tea as the beverage brewed. A need also exists for a filter containing an adsorbent such as, for example, bentonite clays and/or zeolites which could be used to decaffeinate individual cups of liquid such as, for example, coffee, tea or cola.
There is also a need for a filter that is adapted to decaffeinate liquids within 1 or 2 minutes. A need also exists for a filter that is adapted to decaffeinate liquids cleanly without adsorbent particles passing into the liquid/filtrate and without the need for high pressure differentials. There is also a need for a filter that is adapted to successfully decaffeinate liquids at a wide range of temperatures.